Idle curiosity really. There are around 2000 seismograph stations that are available for data access publicly. They are scattered around the world, but where? (Bear in mind while looking at these that there are also many more that are not available to the public, but the proportions are similar. Many networks add some or all of their stations to the world wide network so it is unlikely that there will be significantly more IN PROPORTION than we can see here.
This data is from the IRIS DMC _REALTIME list. You can see the DMC map here but BE WARNED THIS TAKES SEVERAL MINUTES to download EVEN ON BROADBAND. See the end of this post for the full picture.